The invention relates generally to extracorporeal circuits for removing and returning a patient""s bodily fluids. More specifically, the invention relates to a geometries for an extracorporeal circuit for providing treatment to a patient""s bodily fluids with an artificial organ.
Patients with compromised organ function are often treated by using an external artificial organ. For example, an external hemofiltration or dialysis system is typically used to remove waste products from the blood of a patient with compromised kidney function. Blood is removed from the patient, processed in the system, and returned to the patient. Typically, blood is removed through an extracorporeal circuit, generally consisting of tubing and a device to propel the blood. Many extracorporeal circuits have various processing devices disposed throughout the circuit.
Bioartificial organs provide additional benefits in an extracorporeal circuit by performing functions that promote proper homeostasis and that compensate for dysfunction of the natural organ. However, bioartificial organs, in contact with a bodily fluid, often contain living cells that require precise control of temperature, pressure, and flow rate of the fluid in order to maintain their metabolic activity. Typical circuits do not provide optimal control over these important parameters. Accordingly, there is a need in the art for improved extracorporeal fluid circuits that provide optimal control over flow rate, temperature, and pressure within the circuit.
The present invention provides extracorporeal circuits for use in treating a body fluid. Circuits of the invention have a circuit geometry adapted to provide precise control of flow rate, temperature, and pressure through the circuit. Extracorporeal circuits of the invention produce significant advantages, particularly when used in connection with a bioartificial organ, or other fluid circuits. For example, circuits of the invention provide a xe2x80x9cshuntingxe2x80x9d mechanism for fluids if, for example, a blockage occurs in the circuit or in a component with which the circuit is in communication. The shunting mechanism also allows for circuits of the invention to be rapidly attached to and detached from other components or circuits without substantial interruption of fluid flow.
In one aspect of the invention, a circuit for extracorporeal treatment of a body fluid comprises, in serial fluidic communication, an inlet for receiving a body fluid from a patient, a first pump, a first treatment device for processing the body fluid, a second pump, an outlet for returning processed body fluid to the patient and a shunt. The shunt is upstream from the first pump and downstream from the second pump.
In one embodiment of the invention, body fluid is altered prior to entering the inlet. Also in certain embodiments, the shunt connects the inlet to the outlet. A circuit of the invention can include a second treatment device upstream from the inlet, and can include a third pump upstream from the second treatment device. A connector can be disposed between the inlet and the shunt and/or between the outlet and the shunt. The inlet and/or outlet can be a conduit. The inlet, outlet, and/or connector are optionally disposable.
In certain embodiments described above, the first treatment device performs at least one function of a human organ and is preferably a renal assist device. The shunt typically is situated in parallel with the first treatment device. Also, a supply line in fluidic communication with the first treatment device can be added for delivering an additional fluid to the first treatment device. A supply pump can be placed in fluidic communication with the supply line for pumping the additional fluid into the first treatment device. At least a portion of the body fluid receivable within the inlet and at least a portion of the additional fluid receivable within the supply line can combine within the first treatment device. At least one of the fluids can be altered within the first treatment device. A waste receptacle can be in fluidic communication with the first treatment device. At least one heating device can be in association with the circuit. An anticoagulant (for example, but without limitation, heparin) infuser can be in fluidic communication with the circuit. At least one pressure monitor can be in association with the circuit. At least one flow monitor can be in association with the circuit. The pumps can have a pumping rate from about 10 ml/min to about 1000 ml/min. The first pump can have a pumping rate that differs from a second pumping rate of the second pump by a value ranging from about 1 ml/min to about 200 ml/min.
In another aspect of the invention, a method for treating a patient with a compromised bodily function includes the steps of providing a circuit, removing a body fluid from the patient, moving the body fluid through the circuit for processing, and returning processed body fluid to the patient. A preferred circuit is described above and can have any of the features described above. In one embodiment, the compromised bodily function is renal abnormality, the body fluid is blood and/or the body fluid is a blood filtrate.
In another aspect of the invention, a circuit for extracorporeal treatment of a body fluid includes a first section which includes, in serial fluidic communication, an inlet for receiving a body fluid from a patient, a first treatment device for processing the body fluid, a first pump, an outlet for returning processed body fluid to the patient, and a shunt. The shunt connects the inlet with the outlet. The circuit also includes a second section comprising, in serial fluidic communication, a first conduit for receiving an additional fluid, a second pump, the first treatment device for processing the additional fluid, and a third pump. The first treatment device includes a membrane disposed between the body fluid of the first section and the additional fluid of the second section. The circuit can have any of the additional features described above.
In another aspect of the invention, a method for treating a patient with a compromised bodily function includes the steps of providing an extracorporeal circuit, removing a body fluid from the patient, moving the body fluid through a first section of the circuit and moving an additional fluid through a second section of the circuit, and returning processed body fluid to the patient. One circuit is as described immediately above and can have any of the features described above. The method of treating can also have any of the features described above.
In another aspect of the invention, a method for combining two fluids in a treatment device includes the steps of providing a housing that contains a chamber and that contains a plurality of conduits, each conduit having a membrane that defines a lumen and separates the chamber from the lumen of each conduit, and inducing a flow across the membranes from the lumens of the conduits to the chamber. The chamber includes a first inlet and a first outlet and is for containing a first fluid. The first fluid has a first outlet flow rate at the first outlet. The conduits are for containing a second fluid, and the conduits communicate at a second inlet and a second outlet. The second fluid has a second inlet flow rate at the second inlet. The inducing step can include producing a difference between the first outlet flow rate and the second inlet flow rate such that the first outlet flow rate is greater than the second inlet flow rate.